Amador Valley High School Robotics Team / Mbed 2 deprecated performance_timer

This is a small program we use to see how long something takes. It runs the code in the while loop a lot of times and prints out how many us it took. Then this can be divided by the number of iterations to find the time/clock cycles for each iteration.

Dependencies:   mbed-dsp mbed

main.cpp@0:cff63309a8af, 2013-07-08 (annotated)

Committer:
avbotz
Date:
Mon Jul 08 03:58:56 2013 +0000
Revision:
0:cff63309a8af
Initial commit.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
avbotz 0:cff63309a8af 1 #include "mbed.h"
avbotz 0:cff63309a8af 2 #include "dsp.h"
avbotz 0:cff63309a8af 3
avbotz 0:cff63309a8af 4 Serial pc(USBTX, USBRX);
avbotz 0:cff63309a8af 5 DigitalOut myled(LED1);
avbotz 0:cff63309a8af 6 Timer tim;
avbotz 0:cff63309a8af 7
avbotz 0:cff63309a8af 8 int main() {
avbotz 0:cff63309a8af 9 unsigned int i = 0;
avbotz 0:cff63309a8af 10
avbotz 0:cff63309a8af 11 q15_t lad[5], ref[6];
avbotz 0:cff63309a8af 12 q15_t state[1029], in[1024], out[1024];
avbotz 0:cff63309a8af 13 // this loop takes 4 assembly instructions to run per cycle
avbotz 0:cff63309a8af 14 // http://www.wolframalpha.com/input/?i=%282731+us%2F65536%29%2F%281%2F24000000Hz%29
avbotz 0:cff63309a8af 15 arm_iir_lattice_instance_q15 filter = {5, state, ref, lad};
avbotz 0:cff63309a8af 16 tim.start();
avbotz 0:cff63309a8af 17 while (i<100)
avbotz 0:cff63309a8af 18 {
avbotz 0:cff63309a8af 19 arm_iir_lattice_q15(&filter, in, out, 1024);
avbotz 0:cff63309a8af 20 i++;
avbotz 0:cff63309a8af 21 }
avbotz 0:cff63309a8af 22 tim.stop();
avbotz 0:cff63309a8af 23 pc.printf("%d us\n\r",tim.read_us());
avbotz 0:cff63309a8af 24 }
avbotz 0:cff63309a8af 25 //mbed LPC1768 runs at 96 MHz
avbotz 0:cff63309a8af 26 //2731 us=65536 cycles